Method for manufacturing conductive base material, method for manufacturing electronic device, method for manufacturing electromagnetic wave shielding film, and method for manufacturing planar heating element

Abstract

To provide a method for manufacturing a conductive base material and an electronic device which increases the degree of freedom in selecting the base material.SOLUTION: A method for manufacturing a conductive base material includes an arrangement step S10, a sintering step S20, and a transfer step S30. The arrangement step S10 arranges a conductive material containing conductive particles so as to cover at least a part of a base. The sintering step S20 sinters the arranged conductive material, and obtains a conductive pattern. The transfer step S30 transfers the conductive pattern onto a base material from the base.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a method for producing a conductive substrate, a method for producing an electronic device, a method for producing an electromagnetic wave shielding film, and a method for producing a sheet heating element. [Background technology]

[0002] There is a method for forming a conductive pattern such as wiring by applying heat and pressure to a conductive material such as metal powder.

[0003] Patent Document 1 describes that grooves in a substrate are filled with conductive powder, and then pressure and heat are applied to form conductive paths on the substrate.

[0004] Patent Document 2 describes a method for forming a metal wiring layer by filling recesses such as contact holes formed in a semiconductor substrate or the like with fine metal powder and sintering the fine metal powder by hot pressing. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Special Publication No. 60-502233 [Patent Document 2] Japanese Patent Application Publication No. 62-069516 Summary of the Invention [Problem to be solved by the invention]

[0006] However, in the methods of Patent Documents 1 and 2, pressure and heat are applied to the substrate, and therefore it is necessary to use a substrate that can withstand pressure and heat.

[0007] An object of the present invention is to increase the degree of freedom in selecting a substrate in a method for producing a conductive substrate or an electronic device. [Means for solving the problem]

[0008] According to one embodiment of the present invention, there are provided the following methods for producing a conductive substrate, a method for producing an electronic device, a method for producing an electromagnetic wave shielding film, and a method for producing a sheet heating element.

[0009] 1. disposing a conductive material including conductive particles so as to cover at least a portion of a base; sintering the disposed conductive material to obtain a conductive pattern; transferring the conductive pattern from the base to a substrate. A method for manufacturing a conductive substrate. 2. In the method for producing a conductive substrate according to 1., In the transferring step, the conductive pattern is transferred to the substrate via an adhesive layer or a pressure-sensitive adhesive layer. A method for producing a conductive substrate. 3. In the method for producing a conductive substrate according to 1. or 2., The substrate is at least one selected from the group consisting of polyester, polyolefin, polycarbonate, and paper. A method for manufacturing a conductive substrate. 4. In the method for producing a conductive substrate according to any one of 1. to 3., The conductive material is in powder or liquid form. A method for manufacturing a conductive substrate. 5. In the method for producing a conductive substrate according to 4., the conductive material is liquid and contains a solvent; The method for producing the conductive substrate further includes a step of volatilizing the solvent. A method for producing a conductive substrate. 6. In the method for producing a conductive substrate according to any one of 1. to 5., In the step of obtaining the conductive pattern, the conductive material is sintered by applying at least one of pressure and heat to the disposed conductive material. A method for producing a conductive substrate. 7. In the method for producing a conductive substrate according to 6., In the step of obtaining the conductive pattern, the disposed conductive material is heated using at least a heater to sinter the conductive material. A method for producing a conductive substrate. 8. In the method for producing a conductive substrate according to any one of 1. to 7., Between the step of placing the conductive particles and the step of obtaining the conductive pattern, a step of infiltrating the placed conductive material with a component capable of removing an oxide film present on the surface of the conductive particles is further included. A method for producing a conductive substrate. 9. In the method for producing a conductive substrate according to 8., The method further includes a step of applying pressure to the disposed conductive material between the step of disposing and the step of infiltrating. A method for producing a conductive substrate. 10. In the method for producing a conductive substrate according to 9., In the step of obtaining the conductive pattern, the conductive material is sintered by at least applying pressure to the disposed conductive material at a pressure higher than the pressure applied to the disposed conductive material in the step of applying pressure. A method for producing a conductive substrate. 11. The method for producing a conductive substrate according to any one of 1. to 10., The base is provided with a recess, In the placing step, the recess is filled with the conductive material. A method for producing a conductive substrate. 12. The method for producing a conductive substrate according to 11., In the base, the member constituting the side surface of the recess and the member constituting the bottom of the recess are integral with each other. A method for producing a conductive substrate. 13. In the method for producing a conductive substrate according to 11, the base includes a first member having a through hole and a second member different from the first member, The inner surface of the recess is formed by at least a part of the inner surface of the through hole and at least a part of the surface of the second member. A method for producing a conductive substrate. 14. A method for producing an electronic device, comprising producing an electronic device using a conductive substrate obtained by the method for producing a conductive substrate described in any one of 1. to 13. 15. A method for manufacturing an electronic device according to 14, comprising the steps of: The method for manufacturing an electronic device, wherein the electronic device is an RF tag. 16. A method for producing an electromagnetic wave shielding film, comprising producing an electromagnetic wave shielding film using a conductive substrate obtained by the method for producing a conductive substrate described in any one of 1. to 13. 17. A method for producing a sheet heating element, comprising producing a sheet heating element using a conductive substrate obtained by the method for producing a conductive substrate described in any one of 1. to 13. [Effects of the Invention]

[0010] According to the present invention, the degree of freedom in selecting a substrate can be increased in a method for manufacturing a conductive substrate or an electronic device. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a diagram showing an outline of a method for producing a conductive substrate according to a first embodiment. [Figure 2] 1A to 1C are diagrams illustrating a method for manufacturing a conductive substrate according to a first embodiment. [Figure 3] 1A to 1C are diagrams illustrating a method for manufacturing a conductive substrate according to a first embodiment. [Figure 4] 10A and 10B are diagrams illustrating a base and an opposing member according to Modification 1. [Figure 5] 10A and 10B are diagrams illustrating a base and an opposing member according to Modification 2. [Figure 6] 5A to 5C are diagrams illustrating a method for producing a conductive substrate according to a second embodiment. [Figure 7]5A to 5C are diagrams illustrating a method for producing a conductive substrate according to a second embodiment. [Figure 8] 5A to 5C are diagrams illustrating a method for producing a conductive substrate according to a second embodiment. [Figure 9] 10A to 10C are diagrams illustrating a method for producing a conductive substrate according to a third embodiment. [Figure 10] 10A to 10C are diagrams illustrating a method for producing a conductive substrate according to a third embodiment. [Figure 11] 10A to 10C are diagrams illustrating a method for producing a conductive substrate according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0012] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings, like components are designated by like reference numerals, and the description thereof will be omitted as appropriate.

[0013] In this specification, unless otherwise specified, the expression "X to Y" in the description of a numerical range means at least X and at most Y. For example, "1 to 5% by mass" means "at least 1% by mass and at most 5% by mass."

[0014] In the description of groups (atomic groups) in this specification, when a notation does not specify whether the group is substituted or unsubstituted, it encompasses both groups having no substituents and groups having a substituent. For example, the term "alkyl group" encompasses not only alkyl groups having no substituents (unsubstituted alkyl groups) but also alkyl groups having a substituent (substituted alkyl groups).

[0015] In this specification, the term "(meth)acrylic" represents a concept that encompasses both acrylic and methacrylic. The same applies to similar terms such as "(meth)acrylate."

[0016] Unless otherwise specified, the term "organic group" as used herein means an atomic group obtained by removing one or more hydrogen atoms from an organic compound. For example, a "monovalent organic group" refers to an atomic group obtained by removing one hydrogen atom from any organic compound.

[0017] In this specification, the term "electronic device" is used to encompass elements, devices, final products, etc. to which electronic engineering technology is applied, such as semiconductor chips, semiconductor elements, printed wiring boards, electric circuit display devices, information and communication terminals, light-emitting diodes, physical batteries, and chemical batteries.

[0018] (First embodiment) FIG. 1 is a diagram showing an overview of a method for manufacturing a conductive substrate according to a first embodiment. The method for manufacturing a conductive substrate according to this embodiment includes a disposing step S10, a sintering step S20, and a transferring step S30. In the disposing step S10, a conductive material containing conductive particles is disposed so as to cover at least a portion of a base. In the sintering step S20, the disposed conductive material is sintered to obtain a conductive pattern. In the transferring step S30, the conductive pattern is transferred from the base to the substrate.

[0019] According to this method for producing a conductive substrate, a conductive substrate having a conductive pattern formed on a substrate can be obtained.

[0020] In the method for producing a conductive substrate according to this embodiment, sintering for forming a conductive pattern is performed on a base. The conductive pattern is then transferred to a desired substrate. Therefore, the substrate does not need to be able to withstand pressure or heat during sintering, which increases the freedom of substrate selection.

[0021] 2 and 3 are diagrams illustrating a method for manufacturing a conductive substrate 500 according to this embodiment. The method for manufacturing a conductive substrate 500 according to this embodiment will be described in detail below with reference to FIGS. 2 and 3. FIGS. 2 and 3 show cross sections of each element perpendicular to the first surface 102 of the base 10. The same applies to FIGS. 4 to 11. In the example of FIG. 3, the conductive pattern 22 included in the conductive substrate 500 forms, for example, a circuit pattern in plan view. FIG. 3 shows, as an example, a cross section perpendicular to the extension direction of a portion of the conductive pattern 22 that extends linearly in plan view. The same applies to FIGS. 8 and 11.

[0022] In the examples of Figures 2 and 3, the preparation process, placement process, pressurization process, penetration process, sintering process, transfer process, and peeling process are performed in this order, but one or more of the processes other than the placement process, sintering process, and transfer process can be omitted depending on the case.

[0023] <Preparation process> In the example of FIG. 2, in the method for manufacturing the conductive substrate 500, a preparation step of preparing the base 10 is performed before the placement step.

[0024] The base 10 can function as a foundation for forming the conductive pattern 22. The base 10 is made of a material that can withstand the pressure and temperature in the sintering process. The material of the base 10 is not particularly limited, but is, for example, a metal. Examples of metals that can form the base 10 include alloys in which carbon (C) is added to iron. This alloy may further include one or more of chromium (Cr), tungsten (W), molybdenum (Mo), and vanadium (V).

[0025] 2 and 3, the base 10 is provided with a recess 110. When the base 10 is provided with the recess 110, the recess 110 is filled with the conductive material 20 in the placement step, which will be described in detail later.

[0026] The recess 110 is provided on the first surface 102 of the base 10. When viewed in a direction perpendicular to the first surface 102, the shape of the recess 110 is the shape of the desired conductive pattern 22. By appropriately designing the "pattern," it is possible to manufacture a substrate having a pattern structure, such as a conductive film (circuit pattern) that can function as a circuit, a wiring pattern, or a mesh pattern that has electromagnetic wave shielding properties. It is preferable that the "pattern" be appropriately designed depending on the application of the conductive pattern 22 that will ultimately be obtained. One or more recesses 110 are provided on the first surface 102 of the base 10.

[0027] The depth of the recess 110 is not particularly limited, but is, for example, 10 μm to 50 μm. The width of the recess 110 is sufficiently larger than the particle size of the conductive particles, so that the recess 110 can be filled with the conductive material 20 containing the conductive particles.

[0028] In this embodiment, the base 10 includes, for example, a member 100 having a blind hole formed in its surface as a recess 110. This blind hole does not penetrate the base 10 in a direction perpendicular to the first surface 102. The side and bottom of the recess 110 are formed from the same member 100; that is, the member forming the side of the recess 110 and the member forming the bottom of the recess 110 are integrated. The depth of the recess 110 is not variable.

[0029] However, other layers may be provided within the recess 110. For example, a release layer containing a release agent may be formed within the recess 110 prior to the placement step. The release layer may be provided on both the side and bottom surfaces of the recess 110, or only on the side surfaces, or only on the bottom surface. Furthermore, a release layer may also be formed on portions of the first surface 102 other than the recess 110. The release layer may be formed each time the conductive pattern 22 is transferred to the substrate 50, or may be formed after a predetermined number of transfers. The release layer may be formed, for example, by applying a composition containing a release agent to the inner surface of the recess 110. As another example, the release layer may be formed by placing a solid (e.g., powder or sheet-like) release agent within the recess 110. By providing a release layer on the inner surface of the recess 110, the conductive pattern 22 can be easily peeled from the recess 110 of the base 10 in the peeling step described below.

[0030] Examples of the release agent include carnauba wax, stearic acid, montanic acid, metal stearates, polyethylene oxide, and a reaction product of a condensate of an alkene and maleic anhydride with stearyl alcohol, and the release agent may contain one or a combination of two or more selected from these.

[0031] The base 10 may be provided with an air passage 115 that connects the inside of the recess 110 with the outside of the base 10. It is preferable that one opening of the air passage 115 is provided on the inner surface of the recess 110, and the other opening is provided on the outer surface of the base 10. One opening of the air passage 115 may be provided on the side surface or bottom surface of the recess 110. When the air passage 115 is provided in the base 10, gas can flow in and out of the recess 110, making it easier to peel the conductive pattern 22 from the recess 110 of the base 10.

[0032] The shape of base 10 is not limited to the examples in Figures 2 and 3. For example, as will be described later in Modifications 1 and 2, first surface 102 of base 10 does not have to be provided with recess 110.

[0033] <Placement process> In the disposing step, a conductive material 20 containing conductive particles is disposed so as to cover at least a portion of the base 10. In the disposing step, the conductive material 20 may be in powder or liquid form. When the conductive material 20 is in liquid form, the conductive material 20 may be a paste. The viscosity of the conductive material 20 is, for example, 10 to 100 Pa·s. The viscosity of the conductive material 20 can be measured, for example, using an E-type viscometer manufactured by Toki Sangyo Co., Ltd. under conditions of a jig of 3°×R9.7, a rotation speed of 10 rpm, and 25°C. The conductive material 20 may further contain other components in addition to the conductive particles. That is, the conductive material 20 may be a conductive composition.

[0034] The conductive material refers to a material for forming a conductive pattern, and it does not matter whether the material is conductive or not. When placed on the base 10, it is preferable that the conductive particles contained in the conductive material 20 are not substantially sintered. Incidentally, in this embodiment, the conductive particles are usually sintered in a sintering step described below.

[0035] The conductive material 20 includes at least conductive particles. From the viewpoints of availability and good conductivity, the conductive particles preferably include at least one element selected from the group consisting of silver and copper. Specifically, the conductive particles preferably include at least one element selected from the group consisting of particles primarily composed of silver and particles primarily composed of copper. Here, the expression "based on silver" means that the ratio of silver element to all constituent elements in the particle is preferably 50 mol% or more, more preferably 75 mol% or more, even more preferably 90 mol% or more, and particularly preferably 95 mol% or more. Similarly, the expression "based on copper" means that the ratio of copper element to all constituent elements in the particle is preferably 50 mol% or more, more preferably 75 mol% or more, even more preferably 90 mol% or more, and particularly preferably 95 mol% or more.

[0036] It should be noted that the conductive particles may contain elements other than silver and copper, such as gold, aluminum, platinum, palladium, iridium, tungsten, nickel, tantalum, lead, and zinc, as long as the desired conductivity is achieved.

[0037] The conductive particles may contain two or more elements. For example, conductive particles in which the surfaces of copper particles are silver-plated (silver-coated copper particles) are preferably used in this embodiment. Silver-coated copper particles are particles whose main component is copper, and the surfaces of the copper particles are plated with silver in an amount of up to 35 mass% based on the total mass of the particles.

[0038] The particle diameter D at which the cumulative frequency reaches 50% in the volume-based cumulative particle diameter distribution curve obtained when the particle diameter of conductive particles is measured by the laser diffraction scattering method. 50 is preferably 0.5 to 100 μm, more preferably 0.6 to 50 μm, even more preferably 0.7 to 30 μm, and particularly preferably 0.7 to 20 μm. 50By making D appropriately large, it is possible to reduce the number of grain boundaries between conductive particles per unit volume. This is thought to lead to a lower resistivity of the resulting conductive film. 50 It is believed that by ensuring that the particle size is not too large, there will be fewer "gaps" between the conductive particles, which will lead to a lower resistivity of the resulting conductive pattern 22. For the purpose of adjusting or optimizing the particle size distribution or for other purposes, the conductive material 20 may contain two or more different types of conductive particles.

[0039] The conductive particles that can be used in this embodiment can be purchased from, for example, DOWA Electronics Co., Ltd., Fukuda Metal Foil and Powder Co., Ltd., and the like.

[0040] The conductive material 20 may contain a release agent. Examples of the release agent are as described above. When the conductive material 20 contains a release agent, the conductive pattern 22 can be easily peeled from the recess 110 of the base 10 in the peeling step described below.

[0041] From the viewpoint of further reducing the resistivity of the resulting conductive pattern 22, it is preferable that the proportion of conductive particles in the conductive material 20 is high. Specifically, the proportion of conductive particles in the conductive material 20 is preferably 95% by mass or more, more preferably 97% by mass or more, even more preferably 98% by mass or more, and particularly preferably 99% by mass or more. In other words, from the viewpoint of further reducing the resistivity of the resulting conductive pattern 22, it is preferable that the conductive material 20 is substantially free of resin and substantially free of binder. Here, "substantially free of" resin or binder means that the conductive material 20 is completely free of resin or binder, or that the conductive material 20 contains a resin or binder but in such a small amount (for example, 1% by mass or less, specifically 0.5% by mass or less, of the conductive material 20) that the expected effect of using the resin or binder is not obtained.

[0042] On the other hand, from the viewpoint of easily maintaining the shape of the conductive material 20 in the penetration step described below, specifically, from the viewpoint of preventing at least a portion of the conductive material 20 from flowing out due to the oxide film removal solution 40 when the oxide film removal solution 40 in which the component (X) is dissolved or dispersed is penetrated into the conductive material 20 in the penetration step, it is preferable that the conductive material 20 contain one or both of a resin and a binder. The conductive material 20 may contain both a resin and a binder, or may contain only one of a resin and a binder without the other.

[0043] From the viewpoint of easily maintaining the shape of the conductive material 20 while reducing the resistivity of the resulting conductive pattern 22, when the conductive material 20 contains one or both of a resin and a binder, the amount thereof is preferably 1 to 5 mass %, more preferably 2 to 5 mass %, of the total non-volatile components of the conductive material 20.

[0044] Specific preferred examples of the resin or binder include polyvinylpyrrolidone, polyester, epoxy resin, (meth)acrylic resin, polyvinyl acetal, cellulose resin (such as ethyl cellulose), and phenol resin.

[0045] The conductive material 20 may contain a solvent. When the conductive material 20 contains a solvent, the coating or printing properties of the conductive material 20 onto the base 10 are improved. The solvent typically contains an organic solvent. The solvent may contain water as long as the conductive particles can be appropriately dispersed in the solvent. The type of solvent is not particularly limited. Any solvent may be used as long as it does not substantially alter the components in the conductive material 20. The amount of solvent used may be adjusted appropriately depending on the method of arranging the conductive material 20, etc. The amount of solvent used is, for example, 3 to 30 mass %, preferably 5 to 25 mass %, and more preferably 10 to 20 mass % of the total conductive material 20.

[0046] The conductive material 20 may or may not contain various additive components found in conventional ink compositions or conductive pastes.

[0047] When the conductive material 20 is filled in the recess 110 in a powder state, for example, the conductive material 20 is supplied onto the first surface 102 of the base 10 so that it overflows from the recess 110, and then the conductive material 20 is scraped off to the height of the first surface 102, thereby filling the recess 110 with the conductive material 20. In other words, the excess conductive material 20 is removed so that the upper surface of the conductive material 20 in the recess 110 and the first surface 102 of the base 10 are in the same plane. In this way, the conductive material 20 can be filled into the recess 110 so that the upper surface of the conductive material 20 in the recess 110 and the first surface 102 of the base 10 are in the same plane.

[0048] However, in the disposing step, the conductive material 20 may be supplied into the recess 110 in a required amount using a nozzle or the like. In the disposing step, the conductive material 20 may be supplied into the recess 110 by various printing methods such as screen printing, inkjet printing, and dispense printing.

[0049] The present invention is not limited to the above-described example in which the upper surface of the conductive material 20 in the recess 110 and the first surface 102 of the base 10 are flush with each other, and the conductive material 20 may fill only a portion of the recess 110. That is, the conductive material 20 may fill the recess 110 to a level lower than the first surface 102. Alternatively, the conductive material 20 may fill the recess 110 to a level higher than the level of the first surface 102. In other words, the conductive material 20 may be disposed on the base 10 so as to protrude above the recess 110.

[0050] When the conductive material 20 is filled in the recess 110 in a liquid state, the conductive material 20 can be filled in the recess 110 by, for example, applying the conductive material 20 to at least the recess 110 of the base 10. The conductive material 20 may be filled in the recess 110 so that the upper surface of the conductive material 20 in the recess 110 and the first surface 102 of the base 10 are in the same plane, or the conductive material 20 may be filled only in a portion of the recess 110. In other words, the conductive material 20 may be filled in the recess 110 to a level lower than the first surface 102.

[0051] <Pressure process> As will be described in detail later, the method for manufacturing the conductive substrate 500 according to this embodiment may further include, between the placement step and the sintering step, a penetration step in which a component (X) capable of removing an oxide film present on the surface of the conductive particles is penetrated into the conductive material 20 placed on the base 10.

[0052] When the manufacturing method of the conductive substrate 500 according to this embodiment includes a penetration step, a pressurizing step of pressurizing the conductive material 20 placed on the base 10 may be further included between the placement step and the penetration step.

[0053] Whether or not to perform the pressurizing step is optional, but by performing this step, it is possible to prevent the conductive material 20 from flowing out of the recesses 110 when the oxide film removal solution 40 in which the component (X) is dissolved or dispersed is caused to permeate the conductive material 20 on the base 10 in the permeation step. In particular, when the conductive material 20 is a powder, it is preferable to perform the pressurizing step.

[0054] From the viewpoint of preventing the conductive material 20 from flowing out of the recesses 110, it is preferable that the pressure in the pressurizing step be high. On the other hand, from the viewpoint of making it easier for the component (X) to penetrate into the conductive material 20 in the penetration step, it is preferable that the pressure in the pressurizing step is not too high so that an appropriate amount of "gaps" remain in the conductive material 20.

[0055] In the pressing step, the conductive material 20 is pressed in a direction perpendicular to the first surface 102 of the base 10 .

[0056] Specifically, when the pressure applied to the conductive material 20 in the pressing step is P1 and the pressure applied to the conductive material 20 in the sintering step described later is P2, it is preferable that P1 < P2. More specifically, P1 is preferably 0.9 times or less of P2, more preferably 0.75 times or less, and even more preferably 0.6 times or less. That is, the pressure in the pressing step is preferably sufficiently smaller than the pressure required to press or sinter the conductive particles together in the sintering step.

[0057] From various viewpoints, it is also preferable to optimize the values of P1 and P2 respectively. P1 is preferably 1 to 500 MPa, more preferably 10 to 200 MPa, and even more preferably 20 to 100 MPa. When P1 is 1 MPa or more, the effect of suppressing the outflow of the conductive material 20 from the recess 110 in the subsequent penetration step can be surely and sufficiently obtained. Also, when P1 is 500 MPa or less, the "gap" for the penetration of the component (X) is likely to remain sufficiently in the conductive material 20.

[0058] Also, P2 is preferably 10 MPa or more, more preferably 10 to 5000 MPa, even more preferably 20 to 300 MPa, and particularly preferably 30 to 250 MPa. When P2 is 10 MPa or more, the specific resistance of the obtained conductive pattern 22 can be further reduced. Also, when the pressure is 5000 MPa or less, damage to the base 10 can be suppressed. In the method for manufacturing the conductive substrate 500 according to the present embodiment, since the conductive material 20 is pressed on the base 10, there is no need to consider damage to the substrate as in the case of pressing on the substrate. Therefore, a high pressure can be applied, and a conductive pattern 22 having a small specific resistance can be obtained.

[0059] In the pressurizing step, it is preferable to apply heat to the conductive material 20. This is thought to be related to the surface treatment of commercially available conductive particles. Specifically, some surfaces of commercially available conductive particles may be surface treated with an organic substance, and it is thought that applying heat to the conductive material 20 removes or migrates the organic substance on the surface of the conductive particles. This may promote contact between the conductive particles.

[0060] When heat is applied to the conductive material 20 in the pressurizing step, the temperature is, for example, within a range of 50 to 500° C., more preferably 70 to 400° C., and even more preferably 100 to 300° C. Of course, heat does not necessarily need to be applied to the conductive material 20 in the pressurizing step.

[0061] As shown in Fig. 2, in the pressing step, the conductive material 20 is pressed using a pressing member 30. The material of the pressing member 30 is not particularly limited, but it is, for example, a metal. Examples of metals constituting the pressing member 30 include alloys in which carbon (C) is added to iron. This alloy may further contain one or more of chromium (Cr), tungsten (W), molybdenum (Mo), and vanadium (V).

[0062] 2, the pressing member 30 has a protrusion 310 on its surface 300. When the surface 300 of the pressing member 30 is opposed to the first surface 102 of the base 10, the protrusion 310 of the pressing member 30 has a shape and size that allows it to fit into the recess 110 of the base 10. In other words, when viewed in a direction perpendicular to the surface 300, the protrusion 310 has a shape that corresponds to the desired conductive pattern 22. The height of the protrusion 310 from the surface 300 is not particularly limited, but is, for example, 10 to 50 μm.

[0063] In the pressurizing step, the conductive material 20 in the recess 110 is pressed between the bottom surface of the recess 110 and the protrusion 310 by reducing the distance between the surface 300 of the pressurizing member 30 and the first surface 102 of the base 10 while the surface 300 of the pressurizing member 30 is facing the first surface 102 of the base 10. At this time, the pressurizing member 30 may be moved toward the base 10 as shown in FIG. 2 , or the base 10 may be moved toward the pressurizing member 30. The time for which the conductive material 20 is pressed in the pressurizing step is, for example, 1 to 120 seconds.

[0064] Prior to the infiltration step, the pressure member 30 is removed from the base 10 .

[0065] When heat is applied to the conductive material 20 in the pressurizing step, at least one of the base 10 and the pressurizing member 30 may have a heating function. That is, the base 10 may be provided with a heater, the pressurizing member 30 may be provided with a heater, or both the base 10 and the pressurizing member 30 may be provided with heaters. However, the conductive material 20 may also be heated by heaters provided outside the base 10 and the pressurizing member 30. In this case, for example, methods such as light heating and far-infrared heating can be used.

[0066] 2 shows an example in which the surface 300 of the pressing member 30 is generally flat, but the surface 300 of the pressing member 30 may be generally curved, or the pressing member 30 may be generally cylindrical. That is, the pressing step may be performed by roll pressing. In this case, the side surface of the cylinder functions as the surface 300, and a protrusion 310 is provided on the side surface of the cylinder. Then, the side surface of the cylinder is placed opposite the first surface 102, and the cylinder is rotated while pressing the axis of the cylinder toward the base 10, thereby compressing the conductive material 20.

[0067] As another example, if the conductive material 20 is placed on the base 10 in the placement step so that it protrudes above the recess 110, the pressure member 30 may not be provided with the protrusion 310. That is, the surface 300 of the pressure member 30 may be a flat surface without any irregularities. Alternatively, the pressure member 30 may be a cylinder with no irregularities on its side surface.

[0068] <Infiltration process> As described above, the manufacturing method of the conductive substrate 500 according to this embodiment can include a penetration step between the placement step and the sintering step, in which a component (X) capable of removing an oxide film present on the surface of the conductive particles is penetrated into the conductive material 20 on the base 10.

[0069] By carrying out the infiltration step, the sintering of the conductive particles proceeds more easily in the sintering step, and the conductivity of the finally obtained conductive pattern 22 tends to be increased.

[0070] The component (X) is not particularly limited as long as it can remove the oxide film on the surface of the conductive particles. In this specification, the "removal" of the oxide film includes not only the removal of the oxide itself present on the surface of the conductive particles, but also the chemical change (reduction, etc.) of the oxide, which returns the oxide to a non-oxide.

[0071] According to the findings of the present inventors, it is preferable to include at least one selected from the group consisting of organic acids, phosphorus oxoacids, and hydrazine or its derivatives, which are particularly suitable when the conductive particles include copper or silver.

[0072] Examples of organic acids include carboxylic acids such as citric acid, formic acid, acetic acid, malonic acid, malic acid, tartaric acid, ascorbic acid, succinic acid, fumaric acid, and propionic acid. Specific examples of phosphorus oxoacids include phosphinic acid, phosphonic acid, phosphorous acid, phosphoric acid, diphosphate, triphosphate, and metatriphosphate. Among these, phosphinic acid is particularly preferred. Examples of hydrazine or its derivatives include hydrazine itself; hydrazine salts such as hydrazine monohydrochloride, hydrazine dihydrochloride, hydrazine monohydrobromide, and hydrazine sulfate; and other compounds having an -NH-NH structure.

[0073] In addition, from the viewpoint of removing oxide films, a compound having a small pKa in water can be used as component (X). Specifically, a compound having a pKa in water of -5.0 to 5.0 is preferred as component (X), and a compound having a pKa of -4.0 to 4.5 is more preferred as component (X). Incidentally, when component (X) is a polybasic acid, it is preferred that the smallest pKa among the multiple pKas is within the above range.

[0074] Considering only the small pKa and the resulting ability to remove oxide films, it is conceivable to use an inorganic acid such as hydrochloric acid, nitric acid, or sulfuric acid as component (X). However, in consideration of problems that may occur if the acid remains in the conductive material 20, an organic acid is preferred as component (X).

[0075] The pKa value used here can be a value at room temperature (e.g., 25°C). However, from the viewpoint of the removability of the oxide film in the actual process, it may be preferable to use a pKa value at the temperature in the penetration step or sintering step.

[0076] In addition, any compound capable of returning an oxidized film to a non-oxidized state through a reduction reaction can also be used as component (X). For example, a compound having an aldehyde group can sometimes reduce an oxide and can therefore be used as component (X).

[0077] Furthermore, compounds that have a small pKa in water and can return an oxidized film to a non-oxidized state through a reduction reaction are also preferably used as component (X). Formic acid is an example of such a compound. Formic acid has the advantage of being easily volatilized and unlikely to remain in the conductive film.

[0078] Other examples of component (X) include pyrogallol, phenidone, hydroquinone, and orthoaminophenol. These are substances known to function as reducing agents in the field of silver halide photography. If a conductive film having a lower resistivity can be obtained when a certain compound A is impregnated into the conductive material 20 than when it is not impregnated, then that compound A can be used as component (X).

[0079] In the penetration step, when the oxide film removing solution 40 in which the component (X) is dissolved or dispersed is penetrated into the conductive material 20, the concentration of the component (X) in the solution may be adjusted as appropriate. The concentration is adjusted from the viewpoints of allowing a sufficient amount of the component (X) to penetrate into the conductive material 20 and reducing the amount of the remaining component (X) to suppress corrosion and deterioration of the conductive pattern 22.

[0080] The concentration of component (X) in oxide film removing solution 40 is, for example, 0.05 to 50 mol / L, preferably 0.1 to 40 mol / L, more preferably 0.1 to 30 mol / L, even more preferably 0.1 to 10 mol / L, and particularly preferably 0.15 to 5.0 mol / L. Of course, oxide film removing solution 40 containing component (X) at a concentration lower than the concentrations shown here may be used, or oxide film removing solution 40 containing component (X) at a concentration higher than the concentrations shown here (for example, saturated concentration) may be used.

[0081] In the infiltration step, a component (X) capable of removing oxide films on the surfaces of conductive particles is infiltrated into the conductive material 20. In the subsequent sintering step, the conductive material 20 infiltrated with the component (X) is at least pressurized to form the conductive pattern 22.

[0082] From the viewpoint of ease of carrying out the process and ease of permeating the component (X) into the conductive material 20, preferably, in the permeation step, the oxide film removal solution 40 in which the component (X) is dissolved or dispersed is permeated into the conductive material 20. More preferably, in the permeation step, water in which the component (X) is dissolved or dispersed is permeated into the conductive material 20. Using "water" in which the component (X) is dissolved or dispersed is preferable from the viewpoint of reducing the environmental load and ensuring process safety (non-flammability). Of course, an organic solvent in which the component (X) is dissolved or dispersed can also be used.

[0083] In the penetration step, for example, first, an oxide film removal solution 40 containing component (X) is supplied to at least the surface of the conductive material 20 by any method such as dropping, spraying, or immersion, and the liquid containing component (X) is allowed to penetrate into the conductive material 20 under normal pressure or under pressure. Then, a sintering step is performed.

[0084] As another example, the conductive material 20 is exposed to a "gas" containing the component (X) to allow the component (X) to penetrate into the conductive material 20, and then the sintering step is performed. In this case, if the component (X) is a gas at room temperature and normal pressure, the penetration step may be performed at room temperature and normal pressure. Alternatively, if the component (X) is a liquid or solid at room temperature and normal pressure, the component (X) may be heated to vaporize it, and the vaporized component (X) may be brought into contact with the conductive material 20.

[0085] When the sintering step is carried out after the infiltration step, the component (X) that has not infiltrated into the conductive material 20 in the infiltration step may or may not be removed before carrying out the sintering step.

[0086] Furthermore, after the sintering step, a removal step may be performed to remove component (X) remaining on the surface or inside the obtained conductive pattern 22. Specifically, examples of such a step include a step of immersing the obtained conductive pattern 22 on the base 10 or substrate 50 in a liquid (water or an organic solvent) that can dissolve or disperse component (X), or a step of "washing away" the remaining component (X) by pouring a liquid (water or an organic solvent) onto the surface of the conductive pattern 22. Another possible step is to "vaporize and remove" the remaining component (X) by heating the obtained conductive pattern 22.

[0087] Incidentally, when a sintering step is carried out after the infiltration step, there is a possibility that removal of a part of the oxide film by the component (X) may proceed even during the sintering step.

[0088] When the sintering step is performed after the infiltration step, the time between the infiltration step and the sintering step is preferably short so as to prevent the formation of an oxide film again on the surface of the conductive particles from which the oxide film was removed in the infiltration step. Specifically, when the sintering step is performed after the infiltration step, the time from the end of the infiltration step to the start of the sintering step is preferably 1 hour or less, more preferably 30 minutes or less, even more preferably 10 minutes or less, and particularly preferably 1 minute or less.

[0089] Alternatively, in order to prevent an oxide film from being formed again on the surface of the conductive particles from which the oxide film has been removed in the infiltration process, the base 10 and the conductive material 20 after the infiltration process and before the sintering process may be placed in an inert gas atmosphere such as a noble gas or nitrogen gas, a reducing atmosphere, or a vacuum or reduced pressure.

[0090] <Sintering process> In the sintering step, the conductive material 20 placed on the base 10 is sintered by applying at least one of pressure and heat. That is, in the sintering step, only pressure may be applied to the conductive material 20, only heating may be applied, or both heating and pressure may be applied. When both heating and pressure are applied, heating and pressure may be applied simultaneously, or one heating and pressure may be applied sequentially. When heating and pressure are applied sequentially, pressure may be applied after heating, or heating may be applied after pressure.

[0091] In the method for manufacturing the conductive substrate 500 according to this embodiment, at least one of pressure and heat is applied to the conductive material 20 on the base 10, so there is no need to consider damage to the substrate or heat damage, as occurs when at least one of pressure and heat is applied on the substrate. Therefore, at least one of pressure and heat can be applied under conditions that allow a conductive pattern 22 having low resistivity to be obtained.

[0092] When the conductive material 20 is heated in the sintering step, the heating temperature may be set appropriately depending on the type of conductive particles used, etc. The heating temperature may be 50 to 500°C. The heating time may also be set appropriately depending on the type of conductive particles used, etc. The heating time may be, for example, 1 to 120 seconds, preferably 1 to 60 seconds. If a conductive film with sufficiently low resistivity can be obtained, the conductive material 20 does not need to be heated in the sintering step. In particular, when particles containing silver as the main component are used as the conductive particles, a conductive pattern 22 with sufficiently low resistivity can easily be obtained by applying pressure alone.

[0093] In the sintering step, the conductive material 20 placed on the base 10 is heated using at least a heater to sinter the conductive material 20. The heater may be provided in the base 10, the facing member 32, or both the base 10 and the facing member 32. Alternatively, the conductive material 20 may be heated by heaters provided outside the base 10 and the facing member 32. In this case, for example, methods such as optical heating and far-infrared heating can be used. Note that if pressure is not applied in the sintering step, the facing member 32 does not need to be used in manufacturing the conductive substrate 500.

[0094] When pressurizing the conductive material 20 in the sintering step, the conductive material 20 is sintered at a pressure P2 that is higher than the pressure P1 applied to the conductive material 20 in the pressurizing step described above. The pressure P2 applied to the conductive material 20 when pressurizing in the sintering step is as described above. When pressurizing in the sintering step, the pressurizing time is, for example, 1 to 120 seconds.

[0095] When pressure is applied in the sintering process, the conductive material 20 is pressed using the opposing member 32 in the sintering process. The opposing member 32 is made of a material that can withstand the pressure and temperature in the sintering process. The material of the opposing member 32 is not particularly limited, but is, for example, a metal. Examples of metals that constitute the opposing member 32 include alloys in which carbon (C) is added to iron. This alloy may further contain one or more of chromium (Cr), tungsten (W), molybdenum (Mo), and vanadium (V).

[0096] 3, the opposing member 32 has a protrusion 320 on a surface 321. When the surface 321 of the opposing member 32 is opposed to the first surface 102 of the base 10, the protrusion 320 of the opposing member 32 has a shape and size that allows it to fit into the recess 110 of the base 10. In other words, when viewed in a direction perpendicular to the surface 321, the protrusion 320 has a shape that corresponds to the desired conductive pattern 22. The height of the protrusion 320 from the surface 321 is not particularly limited, but is, for example, 10 to 50 μm.

[0097] In the sintering step, the conductive material 20 in the recess 110 is pressed between the bottom surface of the recess 110 and the protrusion 320 by reducing the distance between the surface 321 of the facing member 32 and the first surface 102 of the base 10 while the surface 321 of the facing member 32 is opposed to the first surface 102 of the base 10. At this time, the facing member 32 may be moved toward the base 10, or the base 10 may be moved toward the facing member 32. The time for which the conductive material 20 is pressed in the sintering step is, for example, 1 to 120 seconds.

[0098] In the sintering process, the conductive material 20 is pressed in a direction perpendicular to the first surface 102 of the base 10 .

[0099] 3 shows an example in which the surface 321 of the facing member 32 is generally flat, the surface 321 of the facing member 32 may be generally curved, or the facing member 32 may be generally cylindrical. That is, the pressing step may be performed by roll pressing. In this case, the side surface of the cylinder functions as the surface 321, and a protrusion 320 is provided on the side surface of the cylinder. The conductive material 20 can be pressed by arranging the side surface of the cylinder facing the first surface 102 and rotating the cylinder while pressing the axis of the cylinder toward the base 10.

[0100] As another example, if the conductive material 20 is placed on the base 10 in the placement step so that it protrudes above the recess 110, the opposing member 32 may not be provided with the protrusion 320. That is, the surface 321 of the opposing member 32 may be a flat surface without any irregularities. Alternatively, the opposing member 32 may be a cylinder with no irregularities on its side surface.

[0101] In the placement step, when the conductive material 20 is placed on the base 10 so as to protrude above the recess 110, the conductive material 20 may be pressurized with a sheet sandwiched between the conductive material 20 and the opposing member 32. For example, the sheet may be made of a material whose elastic modulus increases when pressure is applied. Specifically, the sheet may include one or more selected from the group consisting of paper, resin film, glass cloth, rubber-based sheet, and carbon-based sheet. Examples of rubber-based sheets include silicone rubber and fluororubber. Examples of carbon-based sheets include carbon fiber, graphite, and graphene.

[0102] When a pressurizing step is performed, the opposing member 32 used in the sintering step may also serve as the pressurizing member 30 used in the pressurizing step.

[0103] Through the sintering process, a conductive pattern 22 is obtained from the conductive material 20. That is, through the sintering process, the conductive material 20 in the recess 110 is integrated into a film-like structure to form the conductive pattern 22. In the conductive pattern 22, a plurality of conductive particles contained in the conductive material 20 are sintered. In this way, the conductive pattern 22 corresponding to the shape of the recess 110 is formed on the base 10.

[0104] <Transfer process> After the sintering step, a transfer step is performed in which the conductive pattern is transferred to a substrate 50 different from the base 10.

[0105] The substrate 50 is, for example, in the form of a film, sheet, or plate. The substrate 50 is preferably flexible. By employing a flexible substrate 50, a flexible printed circuit (FPC) or a flexible device can be manufactured. However, the substrate 50 may also be a rigid substrate that does not have flexibility.

[0106] Considering cost and end use, the substrate 50 is preferably at least one selected from the group consisting of polyesters such as PET (polyethylene terephthalate) and PEN (polyethylene naphthalate), polyolefins such as polyethylene and polypropylene, polyimide, polycarbonate, glass, epoxy resin, phenolic resin, and paper. The paper may be coated paper (paper whose surface is coated with a coating agent) or ordinary uncoated paper. The substrate 50 is not limited to PET, and any ordinary resin film can be used. The substrate 50 may be transparent or opaque. Examples of opaque resin films include foamed resin films or foamed resin sheets, such as foamed PET film.

[0107] The substrate 50 may be at least one selected from the group consisting of polyester, polyolefin, polycarbonate, and paper. In this embodiment, since the conductive pattern 22 is formed by processing the conductive material 20 on the base 10 in the sintering process, the substrate 50 does not require high levels of heat resistance or pressure resistance. Therefore, materials with low heat resistance and low pressure resistance, such as polyester, polyolefin, polycarbonate, and paper, can also be suitably used as the substrate 50.

[0108] In the transfer step, the conductive pattern 22 is transferred to the substrate 50 via an adhesive layer or pressure-sensitive adhesive layer 52. The target surface of the substrate 50 onto which the conductive pattern 22 is to be transferred preferably has a size sufficient to cover at least one recess 110 entirely.

[0109] The adhesive layer 52 can be made of a resin material. Specific examples include acrylic resin, urethane resin, and silicone resin. The adhesive layer 52 has adhesiveness. The adhesive layer 52 can also be made of a commercially available product. The thickness of the adhesive layer 52 is, for example, 10 to 50 μm.

[0110] Although FIG. 3 shows a case where an adhesive layer 52 is used, this example is not limiting. The conductive pattern 22 may be transferred to the substrate 50 via an adhesive layer. In this case, the adhesive layer is preferably thermosetting or photocurable. The adhesive layer is more preferably formed of a thermosetting resin material or a photocurable resin material. The adhesive layer may contain both a thermosetting resin material and a photocurable resin material. When the substrate 50 is light-transmitting, the adhesive layer can be made photocurable, so that the adhesive layer can be cured by irradiating light from the substrate 50 side. When the substrate 50 is not light-transmitting, the adhesive layer can be made thermosetting, so that the adhesive layer can be cured by heating.

[0111] The adhesive layer may be made of various thermosetting or photocurable resin materials, such as epoxy resin-containing materials, polymerizable (meth)acrylate-containing materials, urethane-based materials, urethane (meth)acrylate-containing materials, and silicone-based materials.

[0112] The adhesive layer may be made of a commercially available product, for example, any of various thermosetting or photocurable resin materials known or commercially available as hard coating agents.

[0113] If the adhesive layer is thermosetting, it is preferable to form the adhesive layer so that the thermosetting proceeds at a heating temperature that does not damage the substrate 50. For example, if the substrate 50 is made of a resin, it is preferable to design the adhesive layer so that the curing reaction proceeds sufficiently when heated at a temperature lower than the glass transition temperature of the resin.

[0114] In the transfer step, the adhesive layer preferably contacts the conductive pattern 22 in an uncured or semi-cured state, more preferably in an uncured state. The adhesive layer is then cured to fix the conductive pattern 22 to the substrate 50. The adhesive layer may be cured before or after the peeling step described below.

[0115] The thickness of the adhesive layer is not particularly limited, but is preferably 1 to 30 μm in order to obtain sufficient adhesiveness. The adhesive layer may be a single layer or may have two or more layers. For example, if the substrate 50 is paper, a two-layer adhesive layer may be used in consideration of penetration into the fibrous paper. In this case, the first adhesive layer closest to the paper plays the role of "sealing."

[0116] The adhesive or pressure-sensitive adhesive layer 52 may be formed on the substrate 50 in advance, as exemplified in Fig. 3. In this case, in the transfer step, the laminate of the substrate 50 and the pressure-sensitive adhesive layer 52 is pressed against the conductive pattern 22 in the recess 110, thereby transferring the conductive pattern 22. At this time, the laminate of the substrate 50 and the pressure-sensitive adhesive layer 52 may be moved toward the conductive pattern 22, as shown in Fig. 3, or the base 10 may be moved toward the laminate of the substrate 50 and the pressure-sensitive adhesive layer 52. At this time, the substrate 50 may be pressed against the conductive pattern 22 using a roll, a planar member, or the like.

[0117] The adhesive or pressure-sensitive adhesive layer 52 may be provided over the entire target surface of the substrate 50 onto which the conductive pattern 22 is to be transferred, or may be provided only in a partial region of the target surface of the substrate 50. The adhesive or pressure-sensitive adhesive layer 52 is provided in at least the target region of the target surface of the substrate 50 onto which the conductive pattern 22 is to be transferred. The adhesive or pressure-sensitive adhesive layer 52 may be provided only in the target region of the target surface of the substrate 50, or may be provided in areas other than the target region.

[0118] As another example, the adhesive or pressure-sensitive adhesive layer 52 may be laminated on the conductive pattern 22 in the recess 110. In this case, in the transfer step, the conductive pattern 22 is transferred by pressing the substrate 50 against the laminate of the adhesive or pressure-sensitive adhesive layer 52 and the conductive pattern 22. At this time, the substrate 50 may be moved toward the laminate of the adhesive or pressure-sensitive adhesive layer 52 and the conductive pattern 22, or the laminate of the adhesive or pressure-sensitive adhesive layer 52 and the conductive pattern 22 may be moved toward the substrate 50. At this time, the substrate 50 may be pressed against the conductive pattern 22 using a roll, a planar member, or the like.

[0119] The adhesive or pressure-sensitive adhesive layer 52 may be provided on both the conductive pattern 22 and an area of ​​the first surface 102 other than the recessed portion 110, or may be provided only on the conductive pattern 22. The adhesive or pressure-sensitive adhesive layer 52 is provided on the conductive pattern 22.

[0120] <Peeling process> After the transfer step, a peeling step is performed. In the peeling step, the substrate 50 is separated from the base 10, thereby peeling the conductive pattern 22 from the base 10. The conductive pattern 22 is peeled from the base 10 while still attached to the substrate 50 via the adhesive or pressure-sensitive adhesive layer 52. In this manner, a conductive substrate 500 including the conductive pattern 22 is obtained. Note that the conductive substrate 500 does not need to be entirely conductive, and includes the substrate 50 and the conductive pattern 22. The conductive substrate 500 may also include an adhesive or pressure-sensitive adhesive layer 52 between the substrate 50 and the conductive pattern 22. If the base 10 has an air passage 115, gas can enter and exit the recess 110, making it easier to peel the conductive pattern 22 from the recess 110 of the base 10 in the peeling step.

[0121] The conductive pattern 22 provided on the substrate 50, i.e., the conductive pattern 22 provided on the conductive substrate 500, is a conductive film having a desired pattern shape. The thickness of the conductive pattern 22 provided on the substrate 50 is preferably 5 to 100 μm, and more preferably 10 to 50 μm.

[0122] According to the method for manufacturing the conductive substrate 500 of this embodiment, the substrate 50 can be selected with a high degree of freedom, and the conductive pattern 22 having good conductivity can be obtained.

[0123] Furthermore, when a recess 110 is provided in the base 10, the conductive pattern is formed within the recess 110, which reduces the spread of the pattern compared to when a conductive pattern is formed by applying conductive ink to a flat substrate, thereby obtaining a conductive pattern with high precision in terms of width, thickness, etc.

[0124] The conductive pattern 22 on the substrate 50 obtained by the manufacturing method including the above-mentioned infiltration step may, but does not necessarily, contain the component (X) on the surface or inside the conductive pattern 22 due to the manufacturing method. That is, the conductive substrate 500 includes the substrate 50 and the conductive pattern 22 provided on at least a portion of the surface of the substrate 50, and the component (X) may be present on the surface or inside the conductive pattern 22.

[0125] The component (X) present on or inside the conductive pattern 22 can be confirmed by various measurement and observation methods. For example, by observing the conductive film with an electron microscope, it may be possible to observe a salt formed by the reaction between the conductive particles and the component (X). In addition, the component (X) present on or inside the conductive pattern 22 may be detected by other methods such as transmission electron microscopy, X-ray diffraction, nuclear magnetic resonance, infrared spectroscopy, ultraviolet-visible absorption spectroscopy, and Raman spectroscopy.

[0126] <Other processes> When the conductive material 20 is liquid and contains a solvent, the method for producing the conductive substrate 500 may further include a step of volatilizing the solvent. Examples of methods for volatilizing the solvent include hot air drying, heating, and light irradiation.

[0127] The step of volatilizing the solvent is preferably carried out after the disposing step and before the sintering step.

[0128] For example, when the solvent is evaporated on the base 10, heating can be performed using a heater provided on the base 10 or a heater provided outside the base 10. The conditions for the heat treatment are not particularly limited as long as the solvent is sufficiently dried, but are adjusted from the viewpoints of sufficiently drying the solvent and preventing deterioration of the conductive particles due to excessive heating. The temperature for the heat treatment is preferably 50 to 150°C, more preferably 80 to 120°C. The time for the heat treatment is preferably 1 to 60 minutes, more preferably 3 to 30 minutes.

[0129] When the conductive material 20 is heated in the sintering step, a cooling step may be further carried out after the sintering step. The cooling step is preferably carried out before the peeling step. In the cooling step, the conductive pattern 22 is cooled. The conductive pattern 22 can be cooled by placing the conductive pattern 22 in an unheated state. The cooling time is, for example, 5 to 120 seconds.

[0130] The above-described steps may be performed continuously or discontinuously. From the viewpoint of mass production, it is preferable to perform the steps continuously. The base 10, pressure member 30, and opposing member 32 can be reused. That is, multiple conductive substrates 500 can be manufactured using the same base 10, pressure member 30, and opposing member 32. Furthermore, it is also possible to form conductive patterns 22 on substrates 50 made of different materials using the same base 10, pressure member 30, and opposing member 32.

[0131] <Electronic device manufacturing method> An electronic device can be manufactured using the conductive substrate 500 obtained as described above. For example, when forming the conductive pattern 22 only on a part of one surface of the substrate 50, by appropriately designing the "pattern," it is possible to manufacture the conductive substrate 500 having a conductive film (circuit pattern) that can function as a circuit. Then, by combining this conductive substrate 500 with other electronic elements, an electronic device can be manufactured.

[0132] Here, some examples of "electronic devices" are described. For clarity, it should be noted that the electronic devices including the conductive substrate 500 obtained by the manufacturing method of the conductive substrate 500 of the present embodiment are not limited to these examples. Sensors: For example, the conductive substrate 500 obtained by the method for producing the conductive substrate 500 of this embodiment can be applied to conductive members / circuits in sensors such as pressure-sensitive sensors and vital sensors. Solar cells: For example, the conductive base material 500 obtained by the method for producing the conductive base material 500 of this embodiment can be applied to current collecting wiring of solar cells. Membrane switch: A membrane switch is a thin sheet-like switch in which circuits and contacts are printed on a film and then laminated. The manufacturing method of the conductive substrate 500 of this embodiment can be applied to form the circuits and contacts. Touch sensor / touch panel: For example, the manufacturing method of the conductive substrate 500 of this embodiment can be applied to form lead wiring in a touch sensor / touch panel. It is also conceivable that the manufacturing method of the conductive substrate 500 of this embodiment can be applied to form transparent electrodes in a touch sensor / touch panel. Flexible substrate: Conventionally, a circuit is formed by first coating a metal film on the entire surface of a flexible film and then removing unnecessary parts of the metal film using chemicals. Instead of this conventional method, it is possible to form a circuit using the manufacturing method of the conductive substrate 500 of this embodiment.

[0133] By using the manufacturing method of the conductive substrate 500 of this embodiment, the surface roughness of the conductive pattern 22 can be reduced, and therefore, when an element such as a chip is mounted on the conductive pattern 22, stability is improved.

[0134] A particularly preferred electronic device is an RF (Radio Frequency) tag. That is, the method for manufacturing the conductive substrate 500 of this embodiment is preferably used to manufacture a conductive circuit such as an antenna portion in an RF tag. For the specific structure of the RF tag, reference can be made to, for example, JP 2003-332714 A and JP 2020-46834 A.

[0135] <Method of manufacturing electromagnetic wave shielding film> As an application other than electronic devices, it is conceivable to manufacture an electromagnetic wave shielding film using the conductive substrate 500 obtained by the manufacturing method of the conductive substrate 500 of the present embodiment. Specifically, an electromagnetic wave shielding film can be manufactured by forming the conductive pattern 22 into a pattern (such as a mesh pattern) specific to the electromagnetic wave shielding film.

[0136] <Method of manufacturing a sheet heating element> As yet another application, it is conceivable to manufacture a sheet heating element using the conductive substrate 500 obtained by the manufacturing method of the conductive substrate 500 of this embodiment. A sheet heating element is an element that generates heat by providing electrical wiring on a substrate and passing an electric current through the wiring. A specific example of a sheet heating element is a sheet heating element for preventing fogging or cold weather, such as on the rear window of a passenger car.

[0137] As described above, according to this embodiment, the conductive material 20 on the base 10 is subjected to at least one of pressure and heat to obtain the conductive pattern 22, and the conductive pattern 22 is transferred to the substrate 50. This improves the freedom of selection of the substrate 50 when manufacturing the conductive substrate 500.

[0138] (Variation 1) 4 is a diagram illustrating the base 10 and the opposing member 32 according to Modification 1. The method for manufacturing the conductive substrate 500 according to Modification 1 is the same as the method for manufacturing the conductive substrate 500 according to the first embodiment, except for the points described below.

[0139] In this modified example, the first surface 102 of the base 10 does not have a recess 110. In the example of Fig. 4, the first surface 102 of the base 10 is flat. Furthermore, in this modified example, the surface 321 of the opposing member 32 does not have a protrusion 320. In the example of Fig. 4, the surface 321 of the opposing member 32 is flat. However, if the opposing member 32 is cylindrical, the surface 321 of the opposing member 32 may be a curved surface.

[0140] If the first surface 102 of the base 10 and the surface 321 of the opposing member 32 are both flat, thickening of the pattern can be suppressed compared to when roll pressing is performed.

[0141] In the sintering process according to this modification, the pattern of the conductive material 20 is pressed between the first surface 102 of the base 10 and the surface 321 of the opposing member 32.

[0142] In the disposing step according to this modification, the conductive material 20 is disposed so as to cover at least a portion of the first surface 102 of the base 10. Specifically, in the disposing step, the conductive material 20 is patterned on the first surface 102 of the base 10. The method for disposing the conductive material 20 on the first surface 102 of the base 10 is not particularly limited, and various coating, printing, and patterning methods can be applied. Examples of printing methods include screen printing, gravure printing, letterpress printing, lithographic printing (offset printing), inkjet printing, transfer printing, and dispensing. As another example, in the disposing step, a film (mask) with holes cut out may be placed on the first surface 102 of the base 10, the conductive material 20 may be disposed on the film and in the holes, and then the film may be removed. By performing the disposing step, a pattern composed of the conductive material 20 is formed on the first surface 102 of the base 10. By appropriately designing this "pattern," it is possible to manufacture a substrate having a pattern structure, such as a conductive film (circuit pattern) that can function as a circuit, a wiring pattern, or a mesh pattern that has electromagnetic wave shielding properties. The "pattern" is preferably designed appropriately depending on the application of the conductive pattern 22 that is finally obtained.

[0143] As described above, in this modification, the conductive material 20 is applied to the first surface 102 of the base 10 in the placement step. Also, in this modification, the conductive material 20 on the first surface 102 may be pressed by a pressure member 30, as will be described later. Then, in the preparation step according to this modification, a release layer containing a release agent may be formed on the first surface 102. The release agent and the release layer are as described in the first embodiment.

[0144] The manufacturing method of the conductive substrate 500 according to this modification may also include a penetration step and a pressurizing step. By carrying out the pressurizing step, it is possible to prevent the conductive material 20 from losing its shape when the oxide film removal solution 40 in which the component (X) is dissolved or dispersed is allowed to penetrate into the conductive material 20 on the base 10 in the penetration step. When the manufacturing method of the conductive substrate 500 according to this modification includes the pressurizing step, the pressurizing member 30 may have the same configuration as the facing member 32. In other words, the surface 300 of the pressurizing member 30 does not need to be provided with the convex portion 310. When the pressurizing step is carried out, the facing member 32 used in the sintering step may also serve as the pressurizing member 30 used in the pressurizing step.

[0145] (Variation 2) 5 is a diagram illustrating the base 10 and the opposing member 32 according to Modification 2. The method for manufacturing the conductive substrate 500 according to Modification 2 is the same as the method for manufacturing the conductive substrate 500 according to Modification 1, except for the points described below.

[0146] In this modification, the first surface 102 of the base 10 does not have a recess 110. In the example of FIG. 5, the first surface 102 of the base 10 is flat. On the other hand, in this modification, the surface 321 of the facing member 32 has a protrusion 320, as in the first embodiment. When the surface 321 of the facing member 32 is opposed to the first surface 102 of the base 10, the protrusion 320 is provided in an area facing the pattern of the conductive material 20 formed on the first surface 102. In the sintering process according to this modification, the pattern of the conductive material 20 is pressed between the first surface 102 of the base 10 and the protrusion 320 of the facing member 32.

[0147] When the manufacturing method of the conductive substrate 500 according to this modification includes a pressurizing step, the pressurizing member 30 can have the same configuration as the facing member 32. That is, a convex portion 310 is provided on the surface 300 of the pressurizing member 30. When the pressurizing step is performed, the facing member 32 used in the sintering step may also serve as the pressurizing member 30 used in the pressurizing step.

[0148] (Second embodiment) The method for producing the conductive substrate 500 according to the second embodiment is the same as the method for producing the conductive substrate 500 according to the first embodiment, except for the points described below.

[0149] 6 to 8 are views illustrating a method for manufacturing a conductive substrate 500 according to the second embodiment. The base 10 according to this embodiment includes a first member 11 having a through-hole 112 and a second member 12 different from the first member 11.

[0150] 6 to 8 , one surface of the first member 11 corresponds to the first surface 102 of the base 10. This surface is also referred to as the first surface 102 of the first member 11. On the other hand, the surface of the first member 11 opposite the first surface 102 is referred to as the second surface 104. The through hole 112 penetrates the first member 11 from the first surface 102 to the second surface 104. When viewed in a direction perpendicular to the first surface 102, the shape of the through hole 112 is the shape of the desired conductive pattern 22.

[0151] A protrusion 123 is provided on the third surface 106 of the second member 12. When viewed in a direction perpendicular to the third surface 106, the shape of the protrusion 123 is the shape of the desired conductive pattern 22. When the first member 11 and the second member 12 are arranged so that the second surface 104 and the third surface 106 face each other, the protrusion 123 of the second member 12 has a structure that allows it to be inserted into the through hole 112 of the first member 11. The distance between the second surface 104 of the first member 11 and the third surface 106 of the second member 12 is variable.

[0152] When the base 10 is composed of the first member 11 and the second member 12, even if the ventilation path 115 is not provided, gas can enter and exit through the gap between the first member 11 and the second member 12 in the recess 110. Therefore, the conductive pattern 22 can be easily removed from the recess 110 in the peeling step.

[0153] In the manufacturing method of the conductive substrate 500 according to this embodiment, the preparation step can be performed in the same manner as the preparation step according to the first embodiment. However, in the preparation step according to this embodiment, the base 10 is formed by combining the first member 11 and the second member 12. Specifically, the base 10 is prepared by inserting the convex portion 123 of the second member 12 into the through hole 112 of the first member 11. By adjusting the distance between the second surface 104 and the third surface 106 so that the end of the convex portion 123 farthest from the third surface 106 is positioned midway through the through hole 112, a concave portion 110 is formed in the first surface 102 of the base 10. That is, the inner surface of the concave portion 110 is formed by at least a portion of the inner surface of the through hole 112 and at least a portion of the surface of the second member 12. More specifically, the side surface of the concave portion 110 is formed by at least a portion of the side surface of the through hole 112, and the bottom of the concave portion 110 is formed by the end face of the convex portion 123 provided on the second member 12.

[0154] In this embodiment, similarly to the first embodiment, the base 10 may be provided with an air passage 115.

[0155] In the method for producing the conductive substrate 500 according to this embodiment, the disposing step can be performed in the same manner as the disposing step according to the first embodiment.

[0156] In the manufacturing method of the conductive substrate 500 according to this embodiment, the pressurizing step may be performed in the same manner as described in the first embodiment. However, in the pressurizing step according to this embodiment, the pressurizing member 30 is placed facing the first surface 102 of the first member 11, and the third surface 106 of the second member 12 is brought close to the second surface 104 of the first member 11, thereby compressing the conductive material 20. The surface of the pressurizing member 30 facing the first surface 102 may be flat. While the conductive material 20 is being pressed, the opening of the first surface 102 of the recess 110 is entirely blocked by the pressurizing member 30. In this way, the conductive material 20 in the recess 110 is pressed between the pressurizing member 30 and the protrusion 123 of the second member 12. That is, the conductive material 20 in the recess 110 is pressed in a direction perpendicular to the first surface 102. Note that the surface of the pressurizing member 30 facing the first surface 102 may have a protrusion. The protrusion may have a size and shape that allows it to fit into the recess 110 of the base 10 .

[0157] In the method for producing the conductive substrate 500 according to this embodiment, the permeation step may be carried out in the same manner as described in the first embodiment.

[0158] In the manufacturing method of the conductive substrate 500 according to this embodiment, the sintering step can be performed in the same manner as the sintering step according to the first embodiment. However, in the sintering step according to this embodiment, when compressing the conductive material 20, the opposing member 32 is placed facing the first surface 102 of the first member 11, and the third surface 106 of the second member 12 is brought close to the second surface 104 of the first member 11, thereby compressing the conductive material 20. The surface of the opposing member 32 facing the first surface 102 may be flat. While compressing the conductive material 20, the opening of the first surface 102 of the recess 110 is entirely blocked by the opposing member 32. In this way, the conductive material 20 in the recess 110 is compressed between the opposing member 32 and the protrusion 123 of the second member 12. That is, the conductive material 20 in the recess 110 is compressed in a direction perpendicular to the first surface 102. Note that the surface of the opposing member 32 facing the first surface 102 may have a protrusion. The protrusion may have a size and shape that allows it to fit into the recess 110 of the base 10 .

[0159] When a pressurizing step is performed, the opposing member 32 used in the sintering step may also serve as the pressurizing member 30 used in the pressurizing step.

[0160] In the method for manufacturing the conductive substrate 500 according to this embodiment, the transfer step can be performed in the same manner as the transfer step according to the first embodiment. However, in the transfer step according to this embodiment, the transfer may be performed by pressing the conductive pattern 22 toward the substrate 50 with the convex portion 123 of the second member 12. With the concave portion 110 of the base 10 covered with the substrate 50, the third surface 106 of the second member 12 is brought close to the second surface 104 of the first member 11, so that the convex portion 123 of the second member 12 can press the conductive pattern 22 toward the substrate 50. At this time, the surface of the substrate 50 opposite the base 10 may be pressed with a flat plate or the like. By pressing the conductive pattern 22 with the convex portion 123, the conductive pattern 22 can be well fixed to the substrate 50.

[0161] In the method for manufacturing the conductive substrate 500 according to this embodiment, the peeling step can be performed in the same manner as the peeling step according to the first embodiment. However, in the peeling step according to this embodiment, peeling may be performed by pushing the conductive pattern 22 toward the substrate 50 with the convex portions 123 of the second member 12. By bringing the third surface 106 of the second member 12 close to the second surface 104 of the first member 11, the conductive pattern 22 can be pushed toward the substrate 50 with the convex portions 123 of the second member 12. By pushing the conductive pattern 22 with the convex portions 123, the conductive pattern 22 can be easily removed from the recesses 110.

[0162] Note that the extraction step may be performed after the sintering step and before the transfer step. In the extraction step, with the opening 110 open, the third surface 106 of the second member 12 is brought close to the second surface 104 of the first member 11, thereby pushing out a part or the whole of the conductive pattern 22 so as to be outside the through-hole 112 of the first member 11 (see FIG. 11 ). At this time, the third surface 106 of the second member 12 may be brought into contact with the second surface 104 of the first member 11.

[0163] In this embodiment, the heater for heating the conductive material 20 may be provided in one or more of the first member 11, the second member 12, the pressure member 30, and the opposing member 32. Alternatively, the heater for heating the conductive material 20 may be provided outside the base 10, the pressure member 30, and the opposing member 32.

[0164] (Third embodiment) The method for producing the conductive substrate 500 according to the third embodiment is the same as the method for producing the conductive substrate 500 according to the second embodiment, except for the points described below.

[0165] 9 to 11 are diagrams illustrating a method for manufacturing a conductive substrate 500 according to a third embodiment. In this embodiment, a heater 14 is provided on the second member 12, and a heater 34 is provided on the opposing member 32. With this configuration, the conductive material 20 in the recess 110 is efficiently heated from both sides. The heater 34 is provided in a partial region of the surface of the opposing member 32 opposite to the surface that faces the base 10. This region is hereinafter referred to as the "heater region of the opposing member 32." Similarly, a heater 14 is provided in a partial region of the surface of the second member 12 opposite to the surface that faces the first member 11. This region is hereinafter referred to as the "heater region of the second member 12."

[0166] In the sintering step according to this embodiment, when the conductive material 20 is pressurized, the conductive material 20 is pressurized using a first pressurizing member 36 and a second pressurizing member 38. When a pressurizing step is performed, the pressurizing step is also performed in the same manner. The first pressurizing member 36 has a protrusion 361. When the conductive material 20 is pressed, the protrusion 361 of the first pressurizing member 36 abuts against the surface of the facing member 32 opposite to the surface facing the base 10, and pushes the facing member 32 toward the base 10. However, the protrusion 361 abuts against an area of ​​the facing member 32 other than the heater area.

[0167] Similarly, the second pressing body 38 is provided with a protrusion 381. When pressing the conductive material 20, the protrusion 381 of the second pressing body 38 comes into contact with the surface of the second member 12 opposite to the surface facing the first member 11, and presses the second member 12 toward the facing member 32. However, the protrusion 381 comes into contact with an area of ​​the second member 12 other than the heater area.

[0168] 10, the manufacturing method of the conductive substrate 500 includes a cooling step. The cooling step is as described in the first embodiment. In the example of FIG. 10, in the cooling step, after the sintering step, the second pressurizing member 38 is separated from the second member 12, and the first pressurizing member 36 is separated from the opposing member 32. Then, the conductive material 20 is cooled by leaving it in a state where it is not heated by the heater.

[0169] 11, the manufacturing method of the conductive substrate 500 includes an extraction step. In the example of Fig. 11, the conductive pattern 22 is extruded above the first surface 102 of the base 10 by moving the first member 11 or the second member 12 until the second surface 104 of the first member 11 contacts the third surface 106 of the second member 12. Then, in the transfer step, the extruded conductive pattern 22 is transferred to the substrate 50.

[0170] 9 to 11 show an example in which the pressurizing step is not performed, but the conductive substrate 500 according to this embodiment may include the pressurizing step. Also, Fig. 9 shows an example in which the oxide film removing solution 40 containing the component (X) is dropped onto the conductive material 20 in the permeation step, but the permeation step according to this embodiment is not limited to this example.

[0171] FIG. 10 shows an example in which heating and pressure are applied in this order in the sintering step, but the order of heating and pressure in the sintering step may be reversed, or heating and pressure may be applied simultaneously.

[0172] Although the embodiments of the present invention have been described above with reference to the drawings, these are merely examples of the present invention, and various other configurations can also be adopted. [Explanation of symbols]

[0173] 10 base 11 First member 12 Second member 14 Heater 20 Conductive Materials 22 Conductive pattern 30 Pressure member 32 opposing member 34 Heater 36 First pressure body 38 Second pressure body 40 Oxide film remover 50 Base material 52 Adhesive layer 100 parts 102 Page 1 104 2nd page 106 3rd page 110 recess 112 Through hole 115 Ventilation Channel 123 Convex 300 sides 310 Convex part 320 Convex 321 sides 361 Convex 381 Convex 500 Conductive substrate

Claims

1. disposing a conductive material including conductive particles so as to cover at least a portion of the base; sintering the disposed conductive material to obtain a conductive pattern; transferring the conductive pattern from the base to a substrate. A method for producing a conductive substrate.

2. The method for producing a conductive substrate according to claim 1, In the transferring step, the conductive pattern is transferred to the substrate via an adhesive layer or a pressure-sensitive adhesive layer. A method for producing a conductive substrate.

3. The method for producing a conductive substrate according to claim 1 or 2, The substrate is at least one selected from the group consisting of polyester, polyolefin, polycarbonate, and paper. A method for producing a conductive substrate.

4. The method for producing a conductive substrate according to claim 1 or 2, The conductive material is in powder or liquid form. A method for producing a conductive substrate.

5. The method for producing a conductive substrate according to claim 4, the conductive material is liquid and contains a solvent; The method for producing the conductive substrate further includes a step of volatilizing the solvent. A method for producing a conductive substrate.

6. The method for producing a conductive substrate according to claim 1 or 2, In the step of obtaining the conductive pattern, the conductive material is sintered by applying at least one of pressure and heat to the disposed conductive material. A method for producing a conductive substrate.

7. The method for producing a conductive substrate according to claim 6, In the step of obtaining the conductive pattern, the disposed conductive material is heated using at least a heater to sinter the conductive material. A method for producing a conductive substrate.

8. The method for producing a conductive substrate according to claim 1 or 2, Between the step of placing the conductive particles and the step of obtaining the conductive pattern, a step of infiltrating the placed conductive material with a component capable of removing an oxide film present on the surface of the conductive particles is further included. A method for producing a conductive substrate.

9. The method for producing a conductive substrate according to claim 8, The method further includes a step of applying pressure to the disposed conductive material between the step of disposing and the step of infiltrating. A method for producing a conductive substrate.

10. The method for producing a conductive substrate according to claim 9, In the step of obtaining the conductive pattern, the conductive material is sintered by at least applying pressure to the disposed conductive material at a pressure higher than the pressure applied to the disposed conductive material in the step of applying pressure. A method for producing a conductive substrate.

11. The method for producing a conductive substrate according to claim 1 or 2, The base is provided with a recess, In the placing step, the recess is filled with the conductive material. A method for producing a conductive substrate.

12. The method for producing a conductive substrate according to claim 11, In the base, the member constituting the side surface of the recess and the member constituting the bottom of the recess are integral with each other. A method for producing a conductive substrate.

13. The method for producing a conductive substrate according to claim 11, the base includes a first member having a through hole and a second member different from the first member, The inner surface of the recess is formed by at least a part of the inner surface of the through hole and at least a part of the surface of the second member. A method for producing a conductive substrate.

14. A method for producing an electronic device, comprising producing an electronic device using a conductive substrate obtained by the method for producing a conductive substrate according to claim 1 or 2.

15. 15. The method for manufacturing an electronic device according to claim 14, comprising: The method for manufacturing an electronic device, wherein the electronic device is an RF tag.

16. A method for producing an electromagnetic wave shielding film, comprising producing an electromagnetic wave shielding film using a conductive substrate obtained by the method for producing a conductive substrate according to claim 1 or 2.

17. A method for producing a sheet heating element, comprising producing a sheet heating element using a conductive substrate obtained by the method for producing a conductive substrate according to claim 1 or 2.

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